[1] By the early 1900s the original single track from Bowenfels to Wallerawang was inadequate for railway operations so plans were made to duplicate that section of line and at the same time ease the grades and flatten some curves.

[1] John Whitton chose to use stone arch construction when denied sufficient funds to use imported wrought iron girders.

It is associated with John Whitton the "father of New South Wales railways", it is an impressive curved sandstone structure on the edge of historic Bowenfels, its construction contributed significantly to the subsequent railway extension to Bathurst and on to western New South Wales and when John Whitton was denied funds to continue with the expensive wrought iron girder bridges he chose the stone arch viaduct for his major bridge works, particularly for the Zig Zag east of Lithgow and the extension west to Wallerawang.

[1] The 1921 viaduct has significance because, it is part of the Bowenfels to Wallerawang duplication, the last of such works dominated by brick arch construction, the curved viaducts, 1870 and 1921, are an impressive pair of structures on the outskirts of historic Bowenfels, the duplication work contributed significantly to the railway extension to Bathurst and to the continued development of Western New South Wales, for land transport to Sydney and with six 12.2-metre (40 ft) clear spans on tall brick piers, it is one of the largest brick arch structures on the New South Wales railways system.

[1] Bowenfels Rail Viaducts was listed on the New South Wales State Heritage Register on 2 April 1999 having satisfied the following criteria.

[1] The place possesses uncommon, rare or endangered aspects of the cultural or natural history of New South Wales.

[1] This Wikipedia article was originally based on Bowenfels Rail Viaducts, entry number 01028 in the New South Wales State Heritage Register published by the State of New South Wales (Department of Planning and Environment) 2018 under CC-BY 4.0 licence, accessed on 2 June 2018.